Cleaning device, image forming apparatus, and method for cleaning

Abstract

A cleaning device includes a semiconductive transfer member which carries charged toner; a first cleaner disposed in contact with the transfer member to electrostatically remove the toner on the transfer member; a second cleaner disposed downstream of the first cleaner along a moving direction of the transfer member to electrostatically remove the toner on the transfer member; and a voltage applicator which applies a bias voltage to the first cleaner, the bias voltage having an opposite polarity to a polarity of the toner. The bias voltage to be applied by the voltage applicator to the first cleaner is higher than a voltage which allows the first cleaner to remove maximum amount of the toner.

What is claimed is: 
     
         1 . A cleaning device comprising:
 a semiconductive transfer member which carries charged toner;   a first cleaner disposed in contact with the transfer member to electrostatically remove the toner on the transfer member;   a second cleaner disposed downstream of the first cleaner along a moving direction of the transfer member to electrostatically remove the toner on the transfer member; and   a voltage applicator which applies a bias voltage to the first cleaner, the bias voltage having an opposite polarity to a polarity of the toner, wherein   the bias voltage to be applied by the voltage applicator to the first cleaner is higher than a voltage which allows the first cleaner to remove maximum amount of the toner.   
     
     
         2 . The cleaning device according to  claim 1 , wherein the bias voltage to be applied by the voltage applicator to the first cleaner is a bias voltage such that the first cleaner removes the toner at a toner removal efficiency of 80% to 95%. 
     
     
         3 . The cleaning device according to  claim 1 , wherein the bias voltage to be applied by the voltage applicator to the first cleaner is a bias voltage such that toner particles having an opposite polarity to a polarity of the toner before being removed by the first cleaner account for 65% or more in a charge distribution of the toner on the transfer member between the first cleaner and the second cleaner. 
     
     
         4 . The cleaning device according to  claim 1 , wherein the second cleaner includes:
 an oppositely-charged-toner cleaner to which a voltage having the same polarity as a normal polarity of the toner is applied, the oppositely-charged-toner cleaner electrostatically removing the toner having an opposite polarity to the normal polarity on the transfer member; and   a normally-charged-toner cleaner to which a voltage having the opposite polarity is applied, the normally-charged-toner cleaner electrostatically removing the toner having the normal polarity on the transfer member.   
     
     
         5 . The cleaning device according to  claim 1 , wherein the first cleaner is a metal roller plated with metal. 
     
     
         6 . The cleaning device according to  claim 5 , wherein the metal plating is electroless nickel plating. 
     
     
         7 . An image forming apparatus comprising a cleaning device, the cleaning device including:
 a semiconductive transfer member which carries charged toner;   a first cleaner disposed in contact with the transfer member to electrostatically remove the toner on the transfer member;   a second cleaner disposed downstream of the first cleaner along a moving direction of the transfer member to electrostatically remove the toner on the transfer member; and   a voltage applicator which applies a bias voltage to the first cleaner, the bias voltage having an opposite polarity to a polarity of the toner, wherein   the bias voltage to be applied by the voltage applicator to the first cleaner is higher than a voltage which allows the first cleaner to remove maximum amount of the toner.   
     
     
         8 . The image forming apparatus according to  claim 7 , wherein the bias voltage to be applied by the voltage applicator to the first cleaner is a bias voltage such that the first cleaner removes the toner at a toner removal efficiency of 80% to 95%. 
     
     
         9 . The image forming apparatus according to  claim 7 , wherein the bias voltage to be applied by the voltage applicator to the first cleaner is a bias voltage such that toner particles having an opposite polarity to a polarity of the toner before being removed by the first cleaner account for 65% or more in a charge distribution of the toner on the transfer member between the first cleaner and the second cleaner. 
     
     
         10 . The image forming apparatus according to  claim 7 , wherein the second cleaner includes:
 an oppositely-charged-toner cleaner to which a voltage having the same polarity as a normal polarity of the toner is applied, the oppositely-charged-toner cleaner electrostatically removing the toner having an opposite polarity to the normal polarity on the transfer member; and   a normally-charged-toner cleaner to which a voltage having the opposite polarity is applied, the normally-charged-toner cleaner electrostatically removing the toner having the normal polarity on the transfer member.   
     
     
         11 . The image forming apparatus according to  claim 7 , wherein the first cleaner is a metal roller plated with metal. 
     
     
         12 . The image forming apparatus according to  claim 11 , wherein the metal plating is electroless nickel plating. 
     
     
         13 . A method for cleaning comprising the steps of:
 (a) carrying charged toner using a semiconductive transfer member;   (b) applying a bias voltage to a first cleaner disposed in contact with the transfer member using a voltage applicator, the bias voltage having an opposite polarity to a polarity of the toner;   (c) electrostatically removing the toner on the transfer member using the first cleaner;   (d) electrostatically removing the toner on the transfer member using a second cleaner disposed downstream of the first cleaner along a moving direction of the transfer member, wherein   the bias voltage to be applied by the voltage applicator to the first cleaner is higher than a voltage which allows the first cleaner to remove maximum amount of the toner.   
     
     
         14 . The method for cleaning according to  claim 13 , wherein the bias voltage to be applied by the voltage applicator to the first cleaner is a bias voltage such that the first cleaner removes the toner at a toner removal efficiency of 80% to 95%. 
     
     
         15 . The method for cleaning according to  claim 13 , wherein the bias voltage to be applied by the voltage applicator to the first cleaner is a bias voltage such that toner particles having an opposite polarity to a polarity of the toner before being removed by the first cleaner account for 65% or more in a charge distribution of the toner on the transfer member between the first cleaner and the second cleaner. 
     
     
         16 . The method for cleaning according to  claim 13 , wherein step (d) includes :
 electrostatically removing the toner having an opposite polarity to a normal polarity of the toner on the transfer member using an oppositely-charged-toner cleaner to which a voltage having the same polarity as the normal polarity is applied; and   electrostatically removing the toner having the normal polarity on the transfer member using a normally-charged-toner cleaner to which a voltage having the opposite polarity is applied.